Color changeable pixel

ABSTRACT

A color changeable pixel comprises a first plate, a second plate and a third plate. The three plates are settled in parallel. The second plate is a deformable and reflective plate. An incident light from one side of the first plate is modulated and only specific frequency light reflects by the second plate. The frequency of the reflected light is related to the distance between the first plate and the second plate. The second plate shifts by the voltage added on the third plate to change the distance between the first plate and the second plate. Therefore, the frequency of the reflected light is altered.

This is a divisional of Application No. 10/670,734 filed Sep. 26, 2003.The entire disclosure(s) of the prior application(s), applicationnumber(s) 10/670,734 is considered part of the disclosure of theaccompanying Divisional application and is hereby incorporated byreference.

BACKGROUND OF THE INVENTION

1. Field of Invention

This invention relates to a color changeable pixel. More particularly,this invention relates to the color changeable pixel of an opticalinterference display plate.

2. Description of Related Art

Due to the properties of being light and small in size, a display plateis favorable in the market of the portable display and displays withspace limits. To date, in addition to Liquid Crystal Display (LCD),Organic Electro-Luminescent Display (OLED) and Plasma Display Panel(PDP), a module of the optical interference display has beeninvestigated.

Referring to U.S. Pat. No. 5,835,255, an array of modulator of thevisible light which can be used in a display plate has been revealed.FIG. 1 shows a cross-section view of a prior art modulator. Everymodulator 100 comprises two walls, 102 and 104. These two walls aresupported by post 106, and a cavity 108 is subsequently formed. Thedistance between these two walls, that is, the length of cavity 108, isD. One of the wall 102 and wall 104 with an absorption factor is asemi-transparent layer which absorbs visible light partially. Another isa light reflective layer which is deformable when the voltage isapplied. When the incident light goes through wall 102 or 104 andarrives at cavity 108, only the visible light with the wavelengthcorresponding to the formula 1.1 is able to be output, that is,2D=Nλ  (1.1),

-   -   wherein N is a natural number.

When the length of cavity 108, D, equals half of the wavelength timesany natural number, a constructive interference is produced and a sharplight wave is emitted. At the mean time, if the observer follows thedirection of the incident light, a reflective light with wavelength λ 1can be observed. Therefore, modulator 100 is “opened”.

FIG. 2 shows a cross-section view of a modulator after a voltage isapplied. As shown in FIG. 2, because of the voltage wall 104 is deformedand falls down towards wall 102. The distance between wall 102 and 104,that is, the length of cavity 108 is not exactly zero. It is d, and dcan be zero. If we used d instead of D in formula 1.1, only the visiblelight with a wavelength fulfilling formula 1.1, which is λ 2, is able toproduce a constructive interference and goes through. Due to the highabsorption rate of wall 102 for light with wavelength λ 2, all theincident visible light would be filtered, therefore the observer whofollows the direction of the incident light is not able to observe anyreflected visible light. The modulator is now “closed”.

An array of modulators comprising modulator 100 is sufficient for asingle colored display plate, but not for a color planar display. Amethod known to the art is to manufacture a pixel which comprises threemodulators with different lengths of the cavities. FIG. 3 and FIG. 4 arecross-section views for the color planar displays comprising modulatorknown to the arts. FIG. 3 shows a cross-section view for a prior artmulti-layered color planar display. Multi-layered color planar display200 comprises three layers, modulators 202, 204 and 206. An incidentlight 208 is reflected by modulators 202, 204 and 206. The wavelengthsof the reflected light are different, for example, they can be redlight, green light and blue light. The reasons to have reflected lightwith three different wavelengths is that the length of the cavities ofmodulators 202, 204 and 206 are different, and also different reflectivemirrors are used. One of the disadvantages of a multi-layered colorplanar display is its poor resolution. Also, as shown in FIG. 3, theblue light is less bright than the red light.

FIG. 4 shows a cross-section view for a prior at matrix color planardisplay. Three modulators, modulators 302, 304 and 306 are formed on asubstrate 300. An incident light 308 is reflected by modulators 302, 304and 306. The wavelengths of the reflected light are different, forexample, they are red light, green light and blue light. The reason tohave reflected light with three different wavelengths is that thelengths of the cavities of modulators 302, 304 and 306 are different. Itis not required to use different reflective mirrors. The resolution isgood, and the brightness of every color light is similar. However,modulators with three different lengths of cavities need to bemanufactured separately, for example, the region for forming themodulators 304 and 306 is shielded by photo-resist while the process forforming the modulator 302 is performed. The manufacturing process iscomplicated and the yield is low. Moreover, the errors introduced duringthe manufacturing process, for instance, the errors of the lengths ofcavities may cause red shift or blue shift. The mistake is uncorrectableand the substrate is wasted.

Therefore, it is important to develop a color optical interferencedisplay plate which has high resolution and brightness and is easy tomanufacture.

SUMMARY OF THE INVENTION

One objective of this invention is to provide a color changeable pixelapplied in the production of multicolor optical interference displayplate. The resolution and brightness of the color changeable pixel ishigh.

The second objective of this invention is to provide a color changeablepixel applied in the production color optical interference displayplate. The manufacturing process is simple and the yield of themanufacture is high.

The third objective of this invention is to provide a color changeablepixel applied in the production of color optical interference displayplate. The correction for the errors introduced during the manufacturingprocess is possible.

According to the objectives of this invention, one of preferredembodiments of the present invention provides a modulator which can beused as a color changeable pixel. It comprises at least a first plate, asecond plate and a third plate. The three plates are set in parallel,and the second plate is settled between the first and the third plate.The first plate is a semi-transparent electrode, and the second plate isa deformable reflective electrode. The two plates are supported by postsand a cavity is formed. The length of the cavity is D.

When the modulator is “open”, there is no voltage applied on the firstand second plate. An incident light from one side of the first plate ismodulated and constructive interference is only happened on the lightwith wavelength fulfilling formula 1.1, which is reflected by the secondplate and goes through the first plate. The frequency of the reflectedlight is related to the length of the cavity. The third plate is anoperating electrode and a voltage can be applied on it. Because thesecond plate shifts when a voltage is applied to the third plate, thedistance between the first and the second plate is changed, that is, thelength of the cavity is changed. As shown in formula 1.1, the wavelengthof the reflected light is altered and different color light, such as redlight, green light or blue light is obtained. In addition, it is knownthat when a second voltage is applied between the first and the secondplate, the second plate deforms and falls towards the first plate. Themodulator is “closed” and no visible light is reflected.

According to the objectives of this invention, another preferredembodiment of the present invention provides a multicolor planar displaywith an array of modulators. An array of modulators is formed on thesame substrate. Every three modulators form a pixel. A pixel comprisesat least a first plate, a second plate and a third plate. The threeplates are set in parallel, and the second plate is settled between thefirst and the third plate. The first plate is a semi-transparentelectrode, and the second plate is a deformable reflective electrode.The two plates are supported by a post and a cavity is formed. Thelength of the cavity is D. When different voltages are applied to two orthree of the three third plates of the three modulators, the movablesecond plates shift and the distances between the first and the secondplates are changed, that is, the length of the cavity is changed.Therefore the lengths of these three cavities are different. When themodulator is “open”, there is no voltage applied to the first and secondplate. According to formula 1.1, the wavelength of the reflected lightis altered due to the change of the length of the cavity. Furthermore,it is known that when a second voltage is applied between the first andthe second plate, the second plate deforms and falls towards the firstplate. The modulator is “closed” and no visible light is reflected.

The color planar display with an array of modulator provided in thisinvention retains the advantages of a matrix color planar display knownto the art, high resolution and brightness, and as well has theadvantages of a multilayered color planar display known to the art,simple manufacturing process and high yield. Besides, because the lengthof the cavity is influenced by the voltage applied on the third plate,the errors of the length of the cavity which is introduced during themanufacturing process can be corrected. Therefore, the yield alsoraises.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary, and are intended toprovide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention. In the drawings,

FIG. 1 is a cross-section view of a prior art modulator.

FIG. 2 is a cross-section view of a prior art modulator after a voltageis applied.

FIG. 3 is a cross-section view for a multi-layered color planar displayknown to the art.

FIG. 4 is a cross-section view for a prior art matrix color display.

FIG. 5A is a cross-section view of the modulator according to onepreferred embodiment of this invention.

FIG. 5B is a cross-section view of the third plate of the modulatoraccording to one preferred embodiment of this invention.

FIG. 6 is a cross-section view of the modulator provided in embodiment 2of this invention according to one preferred embodiment of thisinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In order to provide further information of the structure of a colorchangeable pixel, the first embodiment is provided herein to explain thestructure of every modulator in this invention. In addition, the secondembodiment is provided to give further information of the opticalinterference display plate with an array of modulator.

Embodiment 1

Please refer to FIG. 5A. FIG. 5A shows a cross-section view of themodulator provided in the first embodiment of this invention. Amodulator 500 which functions as a color changeable pixel comprises atleast a first plate 502, a second plate 504 and a third plate 506. Thethree plates are set in parallel, and the second plate 504 is settledbetween the first plate 502 and the third plate 506. The first plate 502and the second plate 504 are selected from the group consisting ofnarrowband mirrors, broadband mirrors, non-metal mirrors, metal mirrorsand the combination thereof.

The first plate 502 is a semi-transparent electrode which comprises aconductive substrate 5021, an absorption layer 5022, and a dielectriclayer 5023. An incident light going through light incidence electrode502 is partially absorbed by the absorption layer 5022. The conductivesubstrate 5021 is made from a conductive transparent material, such asITO and IZO. The absorption layer 5022 is made from metal, such asaluminum or silver. The dielectric layer 5023 is made from siliconoxide, silicon nitrite or metal oxide, which can be obtained byoxidation of part of the absorption layer 5022. The second plate 504 isa deformable reflective electrode. It shifts by the voltage applied. Thesecond plate 504 is made from a dielectric material/conductive semi- ornon-transparent material, or metal/conductive transparent material.

The two plates 502 and 504 are supported by a post 508 and a cavity 510is formed. The length of the cavity is D. The second plate 504 and thethird plate 506 are also supported by a post 512.

When the modulator 500 is “open”, the length of cavity 510 is D. Anincident light 514 from one side of the first plate 502 is modulated incavity 510 and only light with wavelength fulfilling formula 1.1 isreflected by the second plate 504 and goes through the first plate 502.The frequency of the reflected light is related to the length of thecavity.

Referring is made to the FIG. 5B, FIG. 5B is a cross-section view of thethird plate in the modulator. As shown in FIG. 5B, the second plate 504shifts when a voltage V₁ applied to the third plate 506. The secondplate 504 either comes closer to (in position 5041) or farer away from(in position 5042) the third plate 506. The distance between the firstplate 502 and the second plate 504, that is, the length D of the cavity501 is therefore changed and the length of the cavity is changed from Dto D₁ or D₂. As shown in formula 1.1, the wavelength of the reflectedlight is altered due to the change of the length of cavity 501. Lightwith different color, such as red light, green light or blue light isobtained.

Further referring is made to FIG. 5B, it is also shown in FIG. 5B thatwhen a second voltage V₂ is applied between the first plate 502 and thesecond plate 504, the second plate 504 deforms and falls towards thefirst plate 502 (position 5043). Modulator 500 is “closed” and novisible light is reflected.

For a single colored optical interference display plate, the usage ofthe modulator provided in this invention will not complicate themanufacturing process comparing to a modulator known to the art.Besides, because the length of the cavity is influenced by the voltageapplied on the third plate, the errors of the length of the cavityintroduced during the manufacturing process can be corrected. The yieldtherefore increases.

Embodiment 2

Referring is made to FIG. 6, FIG. 6 shows a cross-section view of anarray of modulator provided in the second embodiment of this invention.An array of modulator 600 comprises three modulators: modulator 602,modulator 604 and modulator 606. Every modulator is a color changeablepixel. The structure of modulators is the same as the one provided inembodiment 1. At least one control circuit 608 is connected to the thirdplates 6023, 6043 and 6063. It can apply to all third plates together orseparately. The voltage added to the third plates 6023, 6043 and 6063 iseither identical or different. Since the second plates 6022, 6042 and6062 are movable reflective plates, they are influenced by the voltagesapplied on the third plates 6023, 6043 and 6063. The distance betweenthe first plate 6021, 6041 and 6061 and the second plate 6022, 6042 and6062, that is, the length D of the cavity 610 is changed. The lengths ofthe cavities 6102, 6104 and 6106, that is, d1, d2 and d3 are thereforedifferent. As shown in formula 1.1, the wavelength of the reflectedlight is altered due to the change of the length of cavity. Light withdifferent color, such as red light, green light or blue light isobtained.

Besides, it is known that when a driver circuit 612 is connected tomodulator 602, 604 and 606, a voltage is added between the first plates6021, 6041 and 6061 and the second plates 6022, 6042 and 6062 togetheror separately. The second plate 6022, 6042 and 6062 deform and falltowards the first plate 6021, 6041 and 6061. All or part of themodulators (602, 604 and 606) are “closed”. No visible light isreflected, or light with different color is obtained.

The color planar display with an array of modulator provided in thisinvention retains the advantages of a prior art matrix color planardisplay known to the art, high resolution and brightness, and as wellhas the advantages of a multi-layered color planar display known to theart, simple manufacturing process and high yield. Comparing to a matrixcolor planar display known to the art, the length of the cavities of allmodulators is the same since the change of the length is controlled bythe control IC. Therefore the production of modulators with differentlength of cavities is not required. The manufacturing process is simpleand yield is high. Compared to a multi-layered color planar displayknown to the art, all the modulators are on the same surface, thereforean incident light does not need to go through multi-layered modulators.The resolution and brightness are high. Besides, in a prior artmulti-layered color planar display, in order to make an incident lightto go through a first modulator and be reflected by a second modulatorefficiently, the composition and thickness of the first plate and thesecond plate of three types of modulators are different. Themanufacturing process is actually more complicated than expected.Manufacturing modulators provided in this invention is less difficultthan the modulator known to the art.

In addition, because the length of the cavity is influenced by thevoltage applied on the third plate, the errors of the length of thecavity introduced during the manufacturing process can be corrected. Theyield therefore raises.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of the presentinvention without departing from the scope or spirit of the invention.In view of the foregoing, it is intended that the present inventioncover modifications and variations of this invention provided they fallwithin the scope of the following claims and their equivalents.

1. An optical interference color planar display, comprising: a controlcircuit; a driver circuit; and a modulator array comprising: a firstplate; a second plate; an operating plate; at least one first postlocated between the operating plate and the second plate, wherein thesecond plate is directly connected to the first post; and at least onesecond post located between the first plate and the second plate,wherein a cavity is formed between the first plate and the second plate,and an incident light from one side of the first plate is modulated anda reflected light of only specific frequency is reflected by the secondplate, and the second plate directly contacts and shifts along the firstpost towards the operating plate and directly contacts and shifts alongthe second post towards the first plate by a voltage added on theoperating plate so as to change the distance of the cavity, therebychanging the frequency of the reflected light; wherein the controlcircuit connects to the operating plate to control the length of thecavity of a modulator of the modulator array for reflecting thereflected light with a special wave length, and the driver circuitconnects to the first plate and the second plate to control the on oroff of the modulator.
 2. The optical interference color planar displayof claim 1, wherein the first plate at least comprises: a substrate; anabsorption layer; and a dielectric layer.
 3. The optical interferencecolor planar display of claim 2, wherein the substrate is a transparentconductive substrate.
 4. The optical interference color planar displayof claim 2, wherein a material for forming the dielectric layer issilicon oxide, silicon nitride or metal oxide.
 5. The opticalinterference color planar display of claim 2, wherein the absorptionlayer is made from metal.
 6. The optical interference color planardisplay of claim 2, wherein the substrate is made from IZO glass.
 7. Theoptical interference color planar display of claim 1, wherein the firstplate and the second plate are selected from the group consisting ofnarrowband mirror, broadband mirror, non-metal mirror; and thecombination thereof.
 8. The optical interference color planar display ofclaim 1, wherein the second plate is a deformable plate.
 9. The opticalinterference color planar display of claim 1, wherein the second plateis a moveable plate.
 10. The optical interference color planar displayof claim 1, wherein the second plate at least comprises a dense materialor a semi-transparent material.
 11. The optical interference colorplanar display of claim 10, wherein the semi-transparent material isIZO.
 12. The optical interference color planar display of claim 2,wherein the substrate is made from ITO glass.
 13. The opticalinterference color planar display of claim 10, wherein thesemi-transparent material is ITO.